The MHRA and the global flu vaccine: How the UK is helping shape the world’s flu vaccine

Each year, millions of people across the globe catch influenza, commonly known as the flu. While many recover quickly, flu can be deadly, particularly for older adults, young children, and those with weakened immune systems. In the UK alone, seasonal flu can cause thousands of deaths in a bad year. This is why having an effective and up-to-date flu vaccine is crucial. 

Millions of people around the world prepare for seasonal influenza by getting vaccinated. It's something many of us take for granted – a quick injection at the GP or pharmacy. But behind the scenes, ensuring that vaccine is ready, safe, and effective involves months of international planning, testing, and collaboration. 

At the heart of that global effort is the Medicines and Healthcare products Regulatory Agency (MHRA) – the UK's regulator for medicines and medical devices. The MHRA's role goes far beyond approving medicines for the UK. It also leads on the international stage by hosting the MHRA Global Influenza Meeting, a key event that helps guide the development and delivery of the world's flu vaccines. 

Why the flu vaccine needs updating every year 

Unlike some viruses, like measles, the influenza virus constantly changes and evolves. This means that last year's vaccine may not protect against this year's strains. Each year, scientists and regulators across the world work together to track the latest strains of the virus and decide which ones should be included in the next season's vaccine. 

The World Health Organization (WHO) leads this process through a network of research centres and laboratories known as Global Influenza Surveillance and Response System. However, transforming that scientific research and development into safe, effective, and timely licensed vaccines involves regulators. The MHRA plays a key role in both aspects. 

A meeting 20 years in the making 

This year marks the 40th MHRA influenza meeting, held twice a year for the past 20 years. This year, it was held last week. What began as a European-focused gathering has grown into a major global event, drawing together public health experts, scientists, manufacturers, and regulators from across the world. 

As Dr Othmar Engelhardt, the MHRA's Head of Seasonal Influenza and organiser of the meetings, explains, the MHRA provides “a well-established venue for discussions within the community, bringing together everyone involved in the process of producing and delivering the vaccine after the strains relevant to a particular season are recommended by the WHO strain selection committee.” 

What happens at the meeting? 

The aim of the meeting is to ensure that all players have the information they need to ensure that the provision of the annual flu vaccine is the best it can be – delivered on time, with as few hurdles as possible. It's a forum to share science, streamline processes, and keep the world prepared. 

Topics covered are wide-ranging, including: 

• Update on influenza in the world: Which flu viruses are circulating globally, and which are most likely to pose a threat in the coming season? 

• Reagents and standards: What laboratory materials are available for testing and manufacturing? How can the community help speed up access to these materials? 

• Vaccine production updates: How ready are manufacturers for the upcoming flu season following the WHO strain recommendation, and what's needed to smooth the supply chain? 

Importantly, there is also a focus on zoonotic influenza – flu viruses that jump from animals, such as birds or pigs, to humans. These have the potential to spark the next influenza pandemic, so surveillance and preparation of potential vaccine candidates are essential. 

The disappearance of B/Yamagata 

One notable scientific development in recent years is the apparent disappearance of the B/Yamagata flu lineage since the COVID-19 pandemic. Previously, flu vaccines were quadrivalent, meaning that they contained four virus components (two A types and two B types). Now, many have moved to a trivalent vaccine, with only three components – a shift that required regulatory review and approval. 

Special topics: new vaccines and testing methods 

Day three of the meeting was dedicated to a special topic, namely a workshop on new vaccine platforms and targets for influenza. As technology evolves, researchers are exploring faster and potentially more effective ways to develop, test and produce vaccines – including using mRNA technology and exploring universal flu vaccines (i.e. a vaccine against most flu strains -which would not have to be changed between seasons). 

Another key area is vaccine potency (i.e. dose) testing. The current gold-standard method, called Single Radial Immunodiffusion (SRD), was developed in the 1970s by the National Institute for Biological Standards and Control (NIBSC), now part of the MHRA. Though still recommended by the WHO, researchers are now working on faster and more flexible alternatives, supported by a working group that reports back into the MHRA meeting. 

The 40th meeting also featured reflections from former NIBSC/MHRA staff who were key contributors to SRD methodology, underscoring the UK's longstanding leadership in this space. 

MHRA's international role 

As one of the four WHO Essential Regulatory Laboratories (ERLs) – alongside labs in the US, Japan, and Australia – the MHRA plays a unique role. Its Influenza Resource Centre (IRC) helps develop candidate vaccine viruses (CVVs), ships CVVs and reagents around the world, contributes scientific expertise to vaccine strain selection, prepares biological standards and reagents for use in vaccine manufacture and testing, and our regulatory colleagues advise on the global regulatory process. 

This role also places the MHRA at the forefront of pandemic preparedness, including contributing to the WHO's Pandemic Influenza Vaccine Preparedness framework. This involves all the above. staying alert to emerging zoonotic threats and ensuring the global community is ready to respond. 

A diverse and united audience 

What makes the MHRA Global Influenza Meeting especially valuable is its diversity. It brings together the WHO, regulators, researchers and manufacturers in one open forum. In a field as complex and fast-moving as influenza, open communication is vital. 

As Othmar noted, “The flu field can be difficult because the viruses change all the time, meaning that the vaccines have to change as well.” The meeting provides a rare opportunity for all the key players to align their goals, share progress, and prepare together. 

Why it matters to the UK and the world 

Ultimately, the MHRA's role in facilitating this global collaboration helps ensure that flu vaccines are timely, safe, and effective, not just in the UK but across the world. From setting scientific standards to hosting crucial conversations, the MHRA continues to play a central role in protecting global health. 

For us in the UK, this means protection each winter. For the global community, it means stronger defences against one of the world's most common infectious threats. 

So next time you're offered a flu vaccination, remember that behind that quick appointment lies a year of global planning, science, and collaboration – with a lot of this happening right here in the UK.